feat: accent color transition

src/lib/color.ts

@@ -123,3 +123,48 @@ export function hexToHsl(hex: string) {
   // Return the HSL values as a string
   return [h, s, Math.round(l * 100)]
 }
+
+export function generateTransitionColors(
+  startColor: string,
+  targetColor: string,
+  step: number,
+): string[] {
+  // Convert startColor and targetColor to RGB values
+  const startRed = parseInt(startColor.substring(1, 3), 16)
+  const startGreen = parseInt(startColor.substring(3, 5), 16)
+  const startBlue = parseInt(startColor.substring(5, 7), 16)
+
+  const targetRed = parseInt(targetColor.substring(1, 3), 16)
+  const targetGreen = parseInt(targetColor.substring(3, 5), 16)
+  const targetBlue = parseInt(targetColor.substring(5, 7), 16)
+
+  // Calculate increments for each color channel
+  const redIncrement = (targetRed - startRed) / step
+  const greenIncrement = (targetGreen - startGreen) / step
+  const blueIncrement = (targetBlue - startBlue) / step
+
+  const transitionColors: string[] = []
+
+  // Generate transition colors
+  for (let i = 0; i < step; i++) {
+    // Calculate transition color values
+    const transitionRed = Math.round(startRed + redIncrement * i)
+    const transitionGreen = Math.round(startGreen + greenIncrement * i)
+    const transitionBlue = Math.round(startBlue + blueIncrement * i)
+
+    // Convert RGB values to hex format
+    const hexColor = `#${(
+      (1 << 24) |
+      (transitionRed << 16) |
+      (transitionGreen << 8) |
+      transitionBlue
+    )
+      .toString(16)
+      .slice(1)}`
+
+    // Add transition color to the result array
+    transitionColors.push(hexColor)
+  }
+
+  return Array.from(new Set(transitionColors))
+}

src/providers/root/accent-color-provider.tsx

@@ -1,9 +1,9 @@
+import { useEffect, useRef, useState } from 'react'
 import { useServerInsertedHTML } from 'next/navigation'
 import type { AccentColor } from '~/app/config'
 import type { PropsWithChildren } from 'react'
 
-import { sample } from '~/lib/_'
-import { hexToHsl } from '~/lib/color'
+import { generateTransitionColors, hexToHsl } from '~/lib/color'
 import { noopObj } from '~/lib/noop'
 
 import { useAppConfigSelector } from './aggregation-data-provider'
@@ -30,20 +30,91 @@ const accentColorDark = [
 export const AccentColorProvider = ({ children }: PropsWithChildren) => {
   const { light, dark } =
     useAppConfigSelector((config) => config.color) || (noopObj as AccentColor)
-  useServerInsertedHTML(() => {
-    const accentColorL = sample(light ?? accentColorLight)
-    const accentColorD = sample(dark ?? accentColorDark)
 
-    const lightHsl = hexToHsl(accentColorL)
-    const darkHsl = hexToHsl(accentColorD)
+  const Length = Math.max(light?.length ?? 0, dark?.length ?? 0)
+  const randomSeedRef = useRef((Math.random() * Length) | 0)
+
+  const lightColors = light ?? accentColorLight
+  const darkColors = dark ?? accentColorDark
+  const currentAccentColorLRef = useRef(lightColors[randomSeedRef.current])
+  const currentAccentColorDRef = useRef(darkColors[randomSeedRef.current])
+
+  const [u, update] = useState(0)
+  useEffect(() => {
+    const $style = document.createElement('style')
+
+    const $originColor = document.getElementById('accent-color-style')
+
+    const nextSeed = (randomSeedRef.current + 1) % Length
+    const nextColorD = darkColors[nextSeed]
+    const nextColorL = lightColors[nextSeed]
+    const STEP = 60
+    const INTERVAL = 100
+    const colorsD = generateTransitionColors(
+      currentAccentColorDRef.current,
+      nextColorD,
+      STEP,
+    )
+    const colorsL = generateTransitionColors(
+      currentAccentColorLRef.current,
+      nextColorL,
+      STEP,
+    )
+
+    const timer = setTimeout(function updateAccent() {
+      const colorD = colorsD.shift()
+      const colorL = colorsL.shift()
+      if (colorD && colorL) {
+        currentAccentColorDRef.current = colorD
+        currentAccentColorLRef.current = colorL
+        setTimeout(updateAccent, INTERVAL)
+      } else {
+        randomSeedRef.current = nextSeed
+        currentAccentColorDRef.current = nextColorD
+        currentAccentColorLRef.current = nextColorL
+        update(u + 1)
+      }
+
+      const lightHsl = hexToHsl(currentAccentColorLRef.current)
+      const darkHsl = hexToHsl(currentAccentColorDRef.current)
+
+      const [hl, sl, ll] = lightHsl
+      const [hd, sd, ld] = darkHsl
+
+      $style.innerHTML = `html[data-theme='light'] {
+          --a: ${`${hl} ${sl}% ${ll}%`};
+          --af: ${`${hl} ${sl}% ${ll + 6}%`};
+        }
+        html[data-theme='dark'] {
+          --a: ${`${hd} ${sd}% ${ld}%`};
+          --af: ${`${hd} ${sd}% ${ld - 6}%`};
+        }
+        `
+    }, INTERVAL)
+    document.head.appendChild($style)
+    // FIXME  should remove origin color, if not will not override origin color
+    $originColor?.remove()
+    return () => {
+      clearTimeout(timer)
+
+      setTimeout(() => {
+        document.head.removeChild($style)
+      }, 1000)
+    }
+  }, [Length, darkColors, lightColors, u])
+
+  useServerInsertedHTML(() => {
+    const lightHsl = hexToHsl(currentAccentColorLRef.current)
+    const darkHsl = hexToHsl(currentAccentColorDRef.current)
 
     const [hl, sl, ll] = lightHsl
     const [hd, sd, ld] = darkHsl
 
     return (
       <style
-        data-light={accentColorL}
-        data-dark={accentColorD}
+        id="accent-color-style"
+        data-light={currentAccentColorLRef.current}
+        data-dark={currentAccentColorDRef.current}
         dangerouslySetInnerHTML={{
           __html: `html[data-theme='light'] {
           --a: ${`${hl} ${sl}% ${ll}%`};